Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
  • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
  • H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B9/00—Exposure-making shutters; Diaphragms
  • G03B9/02—Diaphragms
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
  • H10N30/206—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/80—Constructional details
  • H10N30/85—Piezoelectric or electrostrictive active materials
  • H10N30/857—Macromolecular compositions
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/005—Diaphragms
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/42—Piezoelectric device making

Definitions

• the present invention relates generally to electroactive polymers that convert between electrical energy and mechanical energy. More particularly, the present invention relates to electroactive polymers and their use in various applications.
• actuators that convert electrical energy into mechanical work, on a macroscopic or microscopic level.
• actuators are the counterpart of sensors in a control loop that transfer electrical or thermal energy into mechanical work.
• Electro active polymers represent a promising type of actuator, whereby motion is generated by changing its shape or mechanical properties, thereby obviating the problems associated with the more mechanically complex, and heavy conventional electric actuator technologies.
• a concern of the present invention is to provide an electroactive polymer actuator, which includes the capability of improving response speed and operation reliability of a device using electroactive effect.
• the present invention relates to polymers that convert between electrical and mechanical energy.
• a voltage is applied to electrodes contacting a polymer, which may be pre-strained, the polymer deflects. This deflection may be used to do mechanical work.
• the present invention relates to polymers that are pre-strained to improve conversion between electrical and mechanical energy.
• the polymer deflects. This deflection may be used to do mechanical work.
• the pre-strain improves the mechanical response of an electroactive polymer relative to a non-strained polymer.
• the pre-strain may vary in different directions of a polymer to vary response of the polymer to the applied voltage.
• the polymers are not pre- strained. In certain other embodiments, pre-strain may be maintained with an elastic element at the inner diameter of the electrodes.
• the present invention relates to an actuator for converting electrical energy into displacement in a first direction.
• the actuator comprises a circular sheet of elastic, di-electric, transparent polymer material such as Acrylic Tape 4910, Silicone CF 19-2186 and Silicone HS III, a first ring-shaped flexible electrode formed on an upper surface of the laminate, and a second ring- shaped flexible electrode formed on a bottom surface of the laminate.
• the actuator further comprises a voltage applying unit for applying a voltage between the first and second electrodes to cause the laminate to be displaced in response to a change in electric field provided by at least two electrodes.
• the actuator further comprises a ring-shaped rigid frame coupled to the laminate, the frame providing mechanical assistance to maintain the pre-strain and to ensure displacement in a first direction.
• the present invention relates to an actuator for converting electrical energy into linear displacement in a first direction.
• the actuator comprises a pre-stretched di-electric polymer material with upper and lower electrode layers in the shape of a membrane or diaphragm.
• the actuator further comprises two rigid round outer plastic rings that attach to the membrane, e.g., in a sandwich configuration. The two rigid round rings providing mechanical assistance to ensure displacement along an axis orthogonal to the plane of the membrane.
• the actuator may further comprise two small nonconducting non- flexible round inner rings that attach to the center of the membrane thereby forming a hole in the center of the membrane.
• FIGS. IA - ID are cross-section and perspective views of an electroactive polymer actuator according to a first embodiment of the present invention
• FIGS. 2A and 2B are cross-section views of an electroactive polymer actuator according to a second embodiment of the present invention
• FIG. 3 illustrates the membrane actuator shown in Figs. 2A and 2B, further including a stiff non-conducting inner ring
• FIG. 4 is a diagram showing on a linear scale (meters), a graph of displacement (m) versus Mass (kg) for an applied electric field measurement for a special test construction in which different masses or loads (kg) are attached to the inner ring of the membrane actuator of Fig. 3,
• FIG. 5 illustrates a non- limiting example of a laminated polymer stack comprising additional electrode layers arranged such that alternate layers are connected to a common electrode (+/-),
• FIGS. 6A - 6C are cross-sectional views illustrating how several membrane actuators can be combined to increase the absolute movement or force under application of a voltage
• FIG. 7A - 7D illustrate how an actuator deforms in a single direction upon application of an electric field
• FIG. 8 is an illustration of a conductive layer comprised of multiple segments.
• Electroactive polymers of the present invention may be used as an actuator to convert from electrical to mechanical energy.
• polymers of the present invention perform as an actuator by experiencing a displacement either along the axis of thickness (i.e., parallel to a cross- section of the polymer) or orthogonal to the axis of thickness during use (i.e., perpendicular to a cross-section of the polymer).
• a displacement occurs, the polymer is acting as an actuator.
• actuators having a circular shape the present invention contemplates the use of actuators having other shapes.
• other shapes may include, without limitation, squares, rectangles, pentagons, hexagons, octagons and so on. The actuator shape being determined primarily from its intended use.
• actuators employing elastic, non-conducting, di-electric polymers
• present invention also contemplates the use of actuators employing materials other than non-conducting, dielectric polymers (e.g. visco-elastic materials, fluids, and so on)
• materials other than non-conducting, dielectric polymers e.g. visco-elastic materials, fluids, and so on
• actuators having pre-strained polymers the present invention contemplates the use of actuators having non-prestrained polymers.
• a di-electric transparent elastic non- conductive material may comprise different materials including, without limitation, Acrylic Tape 4910, manufactured by the 3M Corporation, Silicone CF 19-2186 from Nusil and Silicone HS III from Dow Corning.
• FIGS. IA and IB illustrate cut away views of an electroactive polymer actuator
• the actuator 10 comprises a flexible upper ring electrode 15 on a top surface of an elastic, di-electric, transparent elastic non- conductive material 20, referred to hereafter as a polymer material 20.
• the polymer material may be pre-strained.
• the electroactive polymer actuator 10 further includes a flexible lower ring electrode 25 on a bottom surface of the transparent polymer material 20.
• the flexible electrodes 15, 25 may be applied to the polymer material 20 in a number of ways, including, without limitation, painting or coating the polymer material 20 on its upper and lower surface with a flexible conductive material or using graphite powder. Of course, other techniques, well known in the art, not explicitly recited herein, may be used to apply the electrodes 15, 25 to the polymer material 20.
• the upper and lower ring electrodes 15, 25 are positioned to cover a substantial portion of the respective upper and lower surfaces of the polymer material 20, leaving an exposed circular portion 30 (see Figs. 1C and ID) substantially in the center of the polymer material 20.
• the electroactive polymer actuator 10 has a voltage applying unit (DC power supply) 40 for applying a voltage between the upper and lower ring electrodes 15, 25 to thereby cause a stationary displacement or movement in the polymer material 20.
• the voltage source may be an AC signal source to obtain stationary displacement or movement patterns in the polymer material 20.
• the upper ring electrode 15 is connected to the positive pole of the DC power supply 40, and the lower ring electrode 25 is connected to the negative pole of the DC power supply 40.
• the power supply may be an AC power supply in other embodiments.
• the electroactive polymer actuator 10 further comprises an outer circular frame 22 which is rigidly attached to the two electrodes 15, 25 and the polymer material 20 substantially at its ends.
• a deformation in the polymer material 20 is such that the dimension in the y-direction of the polymer material 20 compresses or decreases, as indicated in Fig. IB by the compression arrows 27.
• the polymer material 20 is forced to expand in the direction of the inner diameter of the lower and upper ring electrodes 15, 25, as shown by the two expansion arrows labeled 31.
• expansion of the polymer material occurs in the direction of the exposed circular portion 30 which is orthogonal to the thickness of the polymer material 20.
• the direction of expansion of the polymer material 20 can be considered as being perpendicular to a cross-section of the polymer material 20.
• the electroactive polymer actuator 10 of Fig. 1 having the above structure, the inventors have recognized that the electroactive polymer actuator 10 is suitable for use as a camera aperture or diaphragm.
• the polymer material 20 is fully transparent, and the flexible ring electrodes 15 and 25 are non-transparent.
• the inner diameter of both flexible non-transparent ring electrodes 15 and 25 form an aperture diameter of a camera diaphragm, substantially in the center region 30.
• the aperture diameter is reduced (i.e., controlled) as a consequence of the polymer material 20 being compressed thus performing a function associated with a camera aperture.
• the polymer 20, which may be non- transparent, may further comprises a hole substantially in the center region 30.
• the hole 30 forms the aperture diameter of a camera diaphragm. Whenever a voltage is applied, or increased, between the upper and lower ring electrodes 15, 25, the aperture diameter 30 (i.e., hole diameter) is reduced (i.e., controlled) thus performing a function associated with a camera aperture or diaphgram.
• a membrane actuator 200 is shown in a perspective view.
• the membrane actuator 200 has a structure comprised of an elastic non-conductive material 130, referred to hereafter as a di-electric polymer material, which serves as a membrane or diaphragm, and top and bottom, circular, stiff, non-conducting rings 110, 112.
• the top and bottom rings 110, 112 hold the di- electric polymer material 130 pre-stretched and are preferably constructed of a stiff plastic.
• the di-electric polymer material 130 includes two conducting layers 124, 126, comprised of a conducting material (e.g., graphite), which may be painted or coated to the top and bottom surface of the di-electric polymer material 130, as described above with reference to the first embodiment.
• a conducting material e.g., graphite
• the electrodes 124, 126 of the present embodiment do not form a ring shape. Instead, the upper and lower electrodes 124, 126 coat the entire surface of the di-electric polymer material 130.
• the di-electric polymer material 130 expands in a manner causing the polymer material 130 to have a convex shape via the displacement of an attached spring or load (m) 133, as shown in Fig. 2C.
• di-electric polymer material 130 Primary parameters considered in the choice of a di-electric polymer material 130 include the di-electric constant, the Young's Module and the di-electric strength after pre-strain.
• an additional layer of polymer material 130 may be used to form a kind of laminate to protect the di-electric polymer material 130 from being deformed by small scratches or sharp corners which may occur on the top and bottom rings 110, 112.
• a membrane actuator 300 of the third embodiment is similar in construction to the membrane actuator of the second embodiment, as shown in Figs. 2A and 2B, in most respects.
• the membrane actuator 300 includes top and bottom rings 110, 112 for holding the di-electric polymer material 130 pre- stretched and are preferably constructed of a stiff plastic.
• the membrane actuator 300 of Fig. 3 differs from the previously described membrane actuator 200 in one important aspect.
• the membrane actuator 300 of the present embodiment further comprises a stiff non-conducting inner ring 90 which forms a hole 92 in the center of the membrane actuator 300.
• the inner ring 90 facilitates the attachment of different masses (loads) or springs to the membrane actuator 300 to ensure that deformation occurs in a desired direction under the application of an electric field. It should be appreciated that the inner ring 90 further facilitates testing of the membrane actuator 300.
• membrane actuators 300 having the above structure when a switch is turned on, a deformation in the di-electric polymer material 130 is such that the dimension in an axial direction (+/- Z) expands, such that the polymer material 130 forms a convex shape.
• FIG. 4 is a diagram showing on a linear scale (meters), a graph of displacement (m) versus Mass (kg) for an applied electric field measurement for a special test construction in which different masses or loads (kg) are attached to the inner ring 90 of the membrane actuator 300 illustrated in Fig. 3. As shown, the graph exhibits a non-linearity and saturation at higher displacements. It should be understood that it is desirable to operate the membrane actuator 300 in the linear region. As such, it is desirable to use polymer materials that increase the linear operating region. Of course, those skilled in the art will recognize that the use of larger rings, higher electric fields and an additional electrode layers can enhance performance.
• FIG. 5 illustrates a non- limiting example of a laminated polymer stack 400 comprising additional electrode layers arranged such that alternate electrode layers are connected to a common electrode (+/-).
• electrode layers 402, 404 and 406 are connected to a common positive (+) electrode and electrode layers 408 and 410 are connected to a common negative (-) electrode.
• Multiple polymer material layers 412 are shown sandwiched in between the respective electrode layers.
• the laminated polymer stack provides advantages over a single electrode layer in that it is better suited to applications requiring higher displacement forces.
• FIGS. 6A, 6B and 6C are cross-sectional views illustrating how several membrane actuators can be combined to increase the absolute movement and/or force under application of a voltage.
• the respective membrane actuators shown include an inner ring 90 such as the inner ring 90 shown in Fig. 3.
• four position movements are contemplated (i.e., no excitation, applying a voltage to a first membrane actuator, applying a voltage to a second membrane actuator, and applying a voltage to both the first and second membrane actuators).
• two membrane actuators 500, 552 are shown, connected with a stiff non-conducting cylinder which couples an outer peripheral surface of the actuator's respective inner rings 504, 554.
• 5A illustrates the state of the coupled membrane actuators 500, 552 prior to the application of a voltage.
• the application of a voltage to one or both of the actuators 500, 552 determines the degree and direction of movement. For example, upon applying a voltage to the upper membrane actuator 500, the voltage excitation cases the upper membrane actuator 504 to move in the positive y-direction. This movement is aided by a spring like action.
• the coupled membrane actuators move in the negative y-direction. The degree of movement being determined by the voltage potential being applied.
• Fig. 6B two membrane actuators 600, 662 are shown, connected by a hollow cylinder 602.
• the configuration of Fig. 5B is suitable for a wide variety of applications.
• One such application is a lens positioning system in which the actuators 600, 662 are combined in the manner shown in Fig. 5B.
• a small lens (not shown) is placed on top of the inner ring 608 of the uppermost membrane actuator 600 and a second small lens (not shown) is placed on top of the inner ring 610 of the lower membrane actuator 662 .
• a light spot which is reflected at the bottom by a mirror, goes through the middle of the lower membrane 662 and the hollow cylinder 602.
• Fig. 6C two membrane actuators 700, 762 are shown, connected by a hollow cylinder 702.
• the astute reader will recognize that the two membrane actuators 700, 762 of Fig. 6C is a variant of that shown in Fig. 6B. In the present configuration, the two membrane actuators 700, 762 are aligned in the same direction.
• FIG. 7 A - 7D illustrate how an actuator deforms in a single direction upon application of an electric field.
• free boundary dielectric polymer deform during an applied electric field equally into both planar direction.
• Figs.7A - 7D illustrates how an original polymer material 10 with certain dimensions (as shown in Fig. 7A) is pre-stretched to increase performance and is fixed to a ridged frame (as shown in Figs. 7B and 7C), which causes the polymer material 10 to become thinner, thereby causing the active deformation to occur in the opposite planar direction (as shown in Fig. 7D). Movement in an intended direction may then be used to perform mechanical work for a specific task.
• FIG. 8 is an illustration of a conductive layer 90 (i.e., upper and lower ring electrodes 15, 25, as shown in the various figures) comprised of multiple segments 80.
• each segment may be sourced from an independent signal, which can be a DC or an AC signal.
• Fig. 8 also illustrates an elastic, transparent, di-electric membrane 82 and optionally, inner 84 and outer 86 rigid frames for supporting the conductive layer 90.
• the present invention further contemplates the use of transparent optical actuators that are covered with transparent upper and lower electrodes to actively generate deformations of a transparent polymer via a DC or AC signal.
• the present invention further contemplates the use of a feedback loop to control actuator deformations and displacements by adapting the voltage (or charge) on the electrodes.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Mechanical Light Control Or Optical Switches (AREA)
• General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

Applications Claiming Priority (2)

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• 2006
  • 2006-12-18 KR KR1020087014904A patent/KR20080078681A/ko not_active Application Discontinuation
  • 2006-12-18 EP EP06842594A patent/EP1966840A1/en not_active Withdrawn
  • 2006-12-18 US US12/158,351 patent/US20090161239A1/en not_active Abandoned
  • 2006-12-18 JP JP2008546792A patent/JP2009520457A/ja active Pending
  • 2006-12-18 WO PCT/IB2006/054933 patent/WO2007072411A1/en active Application Filing
  • 2006-12-18 CN CNA2006800483138A patent/CN101341606A/zh active Pending

Non-Patent Citations (1)

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